1. Field of the Invention
The present invention relates to methods of manufacture of reverse osmosis product water storage tanks.
2. Prior Art
U.S. Pat. No. 7,601,256 discloses reverse osmosis filtration systems, the disclosure of which is hereby incorporated by reference. That system is what is referred to as a water on water system, in that a product water storage tank with a bladder therein is used, with the bladder being pressurized by squeeze water on the opposite side of the bladder during dispensing of the product water. The system uses a storage tank 20 as shown in FIG. 1, formed by upper and lower injection molded plastic half shells, which are then welded together at the mid-section of the tank, such as by spin welding or by hot plate welding. An opening at the top of the tank 20 receives an assembly, generally indicated by the numeral 22, which includes a product water tube 24 and ports in region 26 for squeeze water ingress and egress.
The bladder in tank 20 is fastened to product water tube 24, and in one embodiment is a flexible plastic member having a thickness of approximately 0.030 inches. The problem, however, is that since the product water tube 24 is fastened to the bladder, either the bladder must sufficiently collapse to be passed through the opening that assembly 22 is pressed into after the two shells are welded together to form tank 20, or alternatively, the bladder must be in the tank when the two shells are welded together. Forcing the bladder through the opening at the top of the tank after the shells are welded together without damage to the bladder is either impossible or not likely, and of course having the bladder within the tank when the two shells are welded together also involves a danger to the bladder because of the heat of the welding process.